1. Field of the Invention
The invention relates generally to non-volatile magnetic memory and particularly to manufacturing magneto (also referred to as “magnetic”) tunnel junction (MTJ) included in the non-volatile magnetic memory.
2. Description of Prior Art
It is well known that current memory is experiencing its manufacturing limitations and is subject to dramatically change in the coming years. Magnetic memory offers an alternative to replacing current memory however, manufacturing of magnetic memory, such as magnetic random access memory (MRAM), is experiencing its own set of problems. Challenges, not easy to overcome, remain largely in the fabrication of scalable and reliable magneto (also referred to as “magnetic”) tunnel junction (MTJ), an active and vital part of the MRAM. An MRAM element is typically made of MTJ and surrounding layers, all formed on a substrate. The MTJ generally serves to save information or data by changing its magnetic orientation, which in some MTJs occurs upon the flow of suitable electrical current through the MTJ.
In these types of MTJs, the MTJ is typically made of a fixed layer, fixed in its magnetic orientation, a barrier layer, and a free layer whose magnetic orientation defines the state of the MTJ's and is switchable according to the current flowing therethrough, relative to the magnetic orientation of the fixed layer.
A tantalum layer is typically formed on top of the MTJ and used to establish a connection to the MTJ for incorporating the MTJ in the MRAM. As discussed above, the MTJ is made of a free layer, typically formed below the tantalum layer, a barrier or MgO layer, formed below the free layer, and a fixed layer formed under the MgO layer. The barrier layer is obviously not a metal layer whereas the free and fixed layers are made of metal. Various layers are formed below the fixed layer and above a metal layer, within or above the substrate, in an effort to help the fixed layer maintain its permanent magnetic orientation. During manufacturing, when etching to form the magnetic memory element (or MRAM element), the metals of the layers below the MgO layer, including the metal layer (typically made of copper) result in some of the metal being re-deposited onto the MgO layer therefore undesirably causing shorting. That is, this detrimentally causes defective MRAM elements because the fixed and free layers are effectively shorted together across the barrier (MgO) layer that is positioned between the fixed and free layers.
What is needed is reliable manufacturing of MRAM elements.